问题描述
我写的应用程序包括，除其他外，一个JButton和JTextArea中。按钮的点击引发长时间的计算，从而在JTextArea中显示的文本。即使计算是漫长的，我可以在旅途中等成绩（想想，例如，近似于圆周率高达100位的应用程序 - 每隔几秒钟，我可以写另一个数字）。问题是，即使我写的（在ActionListener的类是因为该按钮调用的计算）设置JTextArea中的东西的文字，它不同时计算完成后显示的，我只能看到最后结果，经过计算就结束了。
An application I am writing consists, among others, a JButton and a JTextArea. A click on the button leads to a long calculation, resulting in a text shown in the JTextArea. Even though the calculation is long, I can have middle-results on the go (think, for example, of an application which approximates pi up to 100 digits - every few seconds I could write another digit). The problem is, that even if I write (being in the ActionListener class because the button invoked the calculation) to set the text of the JTextArea to something, it isn't shown while the calculation is done, and I can only see the end result, after the calculation is over.
为什么会这样，我怎么能解决这个问题？
Why is it so, and how can I fix it?
感谢您提前。
推荐答案
您的问题是，你正在做的主要的Swing线程，EDT长计算，直到进程完成自己这将会冻结您的整个GUI 。一个解决办法是使用你的计算后台线程，和一个简单的方法来做到这一点使用的SwingWorker创建一个线程后台主Swing线程，在EDT和发布/进程的中期业绩进入的JTextArea。欲了解更多关于SwingWorkers和EDT，请看看这里：
Your problem is that you're doing a long calculation in the main Swing thread, the EDT, and this will freeze your entire GUI until the process has completed itself. A solution is to use a background thread for your calculation, and an easy way to do this it to use a SwingWorker to create a thread background to the main Swing thread, the EDT, and publish/process the interim results into the JTextArea. For more on SwingWorkers and the EDT, please look here: Concurrency in Swing
另外，如果你提供一个体面的我们大概可以给你甚至样品$ C $一个更详细的回应角
Also, if you provide a decent sscce we can probably give you a more detailed response perhaps even with sample code.
一个例子SSCCE：
import java.awt.event.*;
import java.text.DecimalFormat;
import java.util.List;
import javax.swing.*;
public class InterimCalc {
private JPanel mainPanel = new JPanel();
private JTextField resultField = new JTextField(10);
private JButton doItBtn = new JButton("Do It!");
private DecimalFormat dblFormat = new DecimalFormat("0.0000000000");
private SwingWorker<Void, Double> mySwingWorker = null;
public InterimCalc() {
mainPanel.add(doItBtn);
mainPanel.add(resultField);
displayResult(0.0);
doItBtn.addActionListener(new DoItListener());
}
public void displayResult(double result) {
resultField.setText(dblFormat.format(result));
}
public JPanel getMainPanel() {
return mainPanel;
}
private class DoItListener implements ActionListener {
public void actionPerformed(ActionEvent e) {
if (mySwingWorker != null && !mySwingWorker.isDone()) {
mySwingWorker.cancel(true);
}
displayResult(0.0);
mySwingWorker = new MySwingWorker();
mySwingWorker.execute();
}
}
private class MySwingWorker extends SwingWorker<Void, Double> {
private static final int INTERIM_LENGTH = 10000; // how many loops to do before displaying
@Override
protected Void doInBackground() throws Exception {
boolean keepGoing = true;
long index = 1L;
double value = 0.0;
while (keepGoing) {
for (int i = 0; i < INTERIM_LENGTH; i++) {
int multiplier = (index % 2 == 0) ? -1 : 1;
value += (double)multiplier / (index);
index++;
}
publish(value);
}
return null;
}
@Override
protected void process(List<Double> chunks) {
for (Double dbl : chunks) {
displayResult(dbl);
}
}
}
private static void createAndShowUI() {
JFrame frame = new JFrame("Decay Const");
frame.getContentPane().add(new InterimCalc().getMainPanel());
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.pack();
frame.setLocationRelativeTo(null);
frame.setVisible(true);
}
public static void main(String[] args) {
java.awt.EventQueue.invokeLater(new Runnable() {
public void run() {
createAndShowUI();
}
});
}
}
这篇关于在显示文字JTextArea中计算时的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持！